1. Field of the Invention
The present invention relates to a sample processing system suitable for manufacturing, e.g., a semiconductor substrate.
2. Description of the Related Art
A substrate (SOI substrate) having an SOI (Silicon On Insulator) structure is known as a substrate having a single-crystal Si layer on an insulating layer. A device using this SOI substrate has many advantages that cannot be achieved by ordinary Si substrates. Examples of the advantages are as follows.
(1) The integration degree can be increased because dielectric isolation is easy.
(2) The radiation resistance can be increased.
(3) The operating speed of the device can be increased because the stray capacitance is small.
(4) No well step is necessary.
(5) Latch-up can be prevented.
(6) A completely depleted field effect transistor can be formed by thin film formation.
Since an SOI structure has the above various advantages, researches have been made on its formation method for several decades.
As one SOI technology, the SOS (Silicon On Sapphire) technology by which Si is heteroepitaxially grown on a single-crystal sapphire substrate by CVD (Chemical Vapor Deposition) has been known for a long time. This SOS technology once earned a reputation as the most matured SOI technology. However, the SOS technology has not been put into practical use to date because, e.g., a large amount of crystal defects are produced by lattice mismatch in the interface between the Si layer and the underlying sapphire substrate, aluminum that forms the, sapphire substrate mixes in the Si layer, the substrate is expensive, and it is difficult to obtain a large area.
Various SOI technologies have appeared next to the SOS technology. For these SOI technologies, various methods have been examined to reduce crystal defects or manufacturing cost. The methods include a method of ion-implanting oxygen into a substrate to form a buried oxide layer, a method of bonding two wafers via an oxide film and polishing or etching one wafer to leave a thin single-crystal Si layer on the oxide film, and a method of ion-implanting hydrogen to a predetermined depth from the surface of an Si substrate having an oxide film, bonding the!substrate to another substrate, leaving a thin single-crystal Si layer on the oxide film by heating or the like, and peeling one (the other substrate) of the bonded substrates.
The present applicant has disclosed a new SOI technology in Japanese Patent Laid-Open No. 5-21338. In this technology, a first substrate prepared by forming an unporous single-crystal layer (including a single-crystal Si layer) on a single-crystal semiconductor substrate having a porous layer is bonded to a second substrate via an insulating layer. After this, the substrates are separated at the porous layer, thereby transferring the unporous single-crystal layer to the second substrate. This technique is advantageous because the film thickness uniformity of the SOI layer is good, the crystal defect density in the SOI layer can be decreased, the surface planarity of the SOI layer is good, no expensive manufacturing apparatus with special specifications is required, and SOI substrates having about several hundred xc3x85 to 10-xcexcm thick SOI films can be manufactured by a single manufacturing apparatus.
The present applicant has also disclosed a technique in Japanese Patent Laid-Open No. 7-302889, in which first and second substrates are bonded, the first substrate is separated from the second substrate without being broken, the surface of the separated first substrate is planarized, a porous layer is formed again, and the porous layer is reused. Since the first substrate is not wasted, this technique is advantageous in greatly reducing the manufacturing cost and simplifying the manufacturing process.
According to the SOI substrate manufacturing methods proposed by the present applicant, a high-quality SOI substrate can be manufactured. However, to mass-produce SOI substrates, for example, the series of processing operations must be performed at a high speed.
The present invention has been made in consideration of the above situation, and has as its object to provide a processing system suitable for manufacturing, e.g., an SOI substrate.
According to the present invention, there is provided a sample processing system characterized by comprising a turntable on which holding mechanisms for holding samples are mounted at a substantially equal angular interval, a driving mechanism for pivoting the turntable through a predetermined angle to move the samples held by the holding mechanisms to operation positions, and at least one processing apparatus for processing the sample held by the holding mechanism at a predetermined operation position.
In the processing system, the operation positions preferably include, e.g., an inlet position at which the sample for which processing is to: be started is received, and an outlet position at which the processed sample is transferred.
The processing system preferably further comprises, e.g., a conveyor mechanism for transferring the sample to be processed to the holding mechanism located at the operation position as the inlet position and receiving the processed sample from the holding mechanism located at the operation position as the outlet position.
In the processing system, for example, the conveyor mechanism preferably transfers a, plate-like sample in a horizontal state to the holding mechanism located at the inlet position and receives the processed plate-like sample in the horizontal state from the holding mechanism located at the outlet position.
In the processing system, the conveyor mechanism preferably comprises, e.g., a scalar robot.
In the processing system, the holding mechanism preferably has, e.g., a lower holding mechanism for holding the plate-like sample from a lower side.
In the processing system, the holding mechanism preferably has, e.g., a lower holding mechanism for holding the plate-like sample from a lower side, and an upper holding mechanism for holding the plate-like sample from an upper side.
In the processing system, preferably, for example, the sample to be processed has a separation layer, and the at least one processing apparatus comprises a separating apparatus for separating the sample at the separation layer.
In the processing system, for example, the separating apparatus preferably ejects a stream of a fluid toward the separation layer of the sample held by the holding mechanism located at the operation position at which the sample is separated, thereby separating the sample at the separation layer.
In the processing system, preferably, for example, the holding mechanism has a driving source for rotating the sample about an axis perpendicular to the separation layer, and the separating apparatus separates the sample rotated by the driving source.
In the processing system, at least one processing apparatus preferably comprises, e.g., a centering apparatus for centering the sample.
In the processing system, for example, the centering apparatus preferably centers the sample held by the holding mechanism located at the operation position for centering processing.
In the processing system, at least one processing apparatus preferably comprises, e.g., a cleaning apparatus for cleaning a sample separated by the separating apparatus.
In the processing system, the cleaning apparatus preferably cleans the sample held by the holding mechanism located at the operation position for cleaning processing.
In the processing system, at least one processing apparatus preferably comprises, e.g., a cleaning/drying apparatus for cleaning and drying a sample separated by the separating apparatus.
In the processing system, for example, the cleaning/drying apparatus preferably cleans and dries the sample held by the holding mechanism located at the operation position for cleaning/drying processing.
In the processing system, processing operations are preferably parallelly executed at the operation positions.
The processing system preferably further comprises, e.g., a centering apparatus for centering the sample, and a conveyor mechanism for receiving the sample centered by the centering apparatus and transferring the sample to the holding mechanism located at the inlet position.
The processing system preferably further comprises, e.g., a cleaning apparatus for cleaning the sample, and a conveyor mechanism for receiving the sample held by the holding mechanism located at the outlet position and transferring the sample to the cleaning apparatus.
The processing system preferably further comprises, e.g., a cleaning/drying apparatus: for cleaning and drying the sample, and a conveyor mechanism for receiving the sample held by the holding mechanism located at the outlet position and transferring the sample to the cleaning/drying apparatus.
The processing system preferably further comprises, e.g., a centering apparatus for centering the sample, a first conveyor mechanism for receiving the sample centered by the centering apparatus and transferring the sample to the holding mechanism located at the inlet position, a cleaning apparatus for cleaning the sample, and a second conveyor mechanism for receiving the sample held by the holding mechanism located at the outlet position and transferring the sample to the cleaning apparatus.
The processing system preferably further comprises, e.g., a centering apparatus for centering the sample, a first conveyor mechanism for receiving the sample centered by the centering apparatus and transferring the sample to the holding mechanism located at the inlet position, a cleaning/drying apparatus for cleaning and drying the sample, and a second conveyor mechanism for receiving the sample held by the holding mechanism located at the outlet position and transferring the sample to the cleaning/drying apparatus.
The processing system preferably further comprises, e.g., a third conveyor mechanism for transferring the sample to the centering apparatus and receiving the sample from the cleaning apparatus.
The processing system preferably further comprises, e.g., a third conveyor mechanism for transferring the sample to the centering apparatus and receiving the sample from the cleaning/drying apparatus.
The processing system preferably further comprises, e.g., an apparatus for processing the sample before the sample is transferred to the holding mechanism located at the inlet position.
The processing system preferably further comprises, e.g., an apparatus for processing the sample after the sample is received from the holding mechanism located at the outlet position.
In the processing system, the separation layer is preferably, e.g., a layer having a fragile structure.
In the processing system, the layer having the fragile structure is preferably, e.g., a porous layer.
In the processing system, the layer having the fragile structure is preferably, e.g., a microcavity layer.
In the processing system, the sample to be processed is preferably, e.g., a semiconductor substrate.
In the processing system, preferably, the sample to be processed is formed by, e.g., bonding a first substrate and a second substrate and has a layer having a fragile structure as the separation layer.
In the processing system, the sample to be processed is preferably formed by, e.g., forming a porous layer on a surface of a first semiconductor substrate, forming an unporous layer on the porous layer, and bonding a second substrate to the unporous layer.